Pulley



y 1949- s. T. FARRELL ET AL 2,469,297

PULLEY Original Filed March 24, 1944 Patented May 3,1949 I UNITED STATES i tdlTENT OFFICE PULLEY Sydney T. Farrell and Frederick L. Farrell, Belmont, Mass.

Griginai application March 24, 1944, Serial No. 527,867. Divided and this application July 24, 1946, Serial No. 685,819

Claims. (Cl. 74-230.5)

l 2 lhis invention relates to belt drives, and it aims with the bosses b entering the grooves a of the to improve the pulleys used in mechanisms of hub section 2., the assembling movement being this type with a view both to reducing the liability in a direction generally parallel to the axis of of braking a belt when heavy increases in load the pulley.

are suddenly applied to it, as for example, when 5 Preferably the ends of adjoining sections of the a clutch is let in too quickly, and also to minimize rim are interlocked with each other, as best shown the strain imposed on the machinery driven by in Figs. 2 and 3. As there illustrated, the section the pulley under such circumstances. d has an extension 9 of the same general form The nature of the invention will be readily unas one of the elements b, and it extends into a derstood from the following description when socket h similar to the recesses a, formed in the read in connection with the accompanying drawsection e. The walls of these two parts g and .h ings, and the novel features will be particularly are isolated, one from the other, by an intervenpointed out in the appended claims. ing cushioning member 2'. The same construc- In the drawings, tion is provided at each of the joints, so that Fig. 1 is a side elevation of a pulley embodying while this rim is interlocked with the hub section this invention; through the medium of the cushioning material Fig. 2 is a plan view of a small section of the t, the rim sections themselves are interlocked periphery of the pulley shown in Fig. 1; and with each other, through the cushionin layer 2',

Figs. 3 and 4 are sectional views taken, respecagainst separation circumferentially,

tively, on the lines 33, 2, and =l Fig. In order to prevent any movement of the three The pulley structure shown in the drawings parts 2, 3 and 4 axially, one relatively to the other,

comprises a central or hub section 2 and a sepatwo retaining plates, indicated at 5 and 5, respecrate rim section indicated, in general at 3, the tively, are secured to the hub member 3 by bolts 1 latter encircling the hub section. This hub secwhere they overlie lateral surfaces of both the tion is provided with a series of recesses or grooves members '2 and 3 and also the lateral edges of a, each having an approximately cylindrical the cushioning material 4.

cross-sectional form, which open into the periph- The sections of cushioning material 4 and i eral surface of the hub section, the axes of these may be made of rubber, either natural or syngrooves or recesses lying parallel to the axis of thetic, or of other plastic compositions having the pulley. The rim 3 is provided with integral resilient properties, and they may be compounded lugs or ribs 1) which are positioned in the respecby methods well known in the plastic art to give tive grooves a, and are of essentially the same them the desired degree of hardness and elascross-sectional form as the latter, but they are ticity. For this purpose they may be reinforced, sumciently smaller in diame er than the recesses when necessary, by fillers of a granular, pulveruto provide between them the space necessary to lent, or fibrous character. Or, they may consist accommodate a molded layer of cushioning mateof fabric impregnated, coated, or laminated with rial 4. As clearly shown in Figs. 1 and 3, the ribs elastic compositions so as to give them the neceshave approximately semicircular sides and the sary degree of toughness and stability for mee o v s re of mplem t l shape to ve chanical purposes, while still having the desired them. Thus the maximum width circumferen- 4 .1 cushioning properties. Also, these parts may be t y of each rib is at an intermediate point in perforated or manufactured by any desired its radial length, and this is also true of each method to give them sufiicient porosity for cushgroove. ioning purposes. Whether or not such porosity Preferably the rim is made in a plurality of is necessary will depend upon the nature of the sections, the number of which is selected in accomposition and the degree of cushioning effect Co danc W the dimfinsio'fls 0f e p y and required. If these cushioning members are made the requirements of the service to which it is to of rubber, which is substantially non-porous, then be put. In the particular construction shown they should be provided with cut-outs or holes,

there are four of these sections, indicated in Fig. 1 as best shown in Figs. 3 and 4, or made in some at c, d, e and f. Usually it will be found most manner such that the rubber can flow under comconvenient to make the cushioning material 4 in pression. While some lateral flow is provided by corresponding sections. The parts are assembled the fact that the edges of the rubber inserts 4 by first securing the rim sections together to are confined at only relatively narrow areas,

complete this member, and then sliding it and where they bear against the retaining plates 5 the cushioning material 4 edgewise on to the hub, and 5, the degree of flow so provided may not be sufiicient to give the desired results, in some instances, and perforations, or some equivalent constructions, such as those indicated at 3 and 4, then become desirable because of the fact that solid rubber is substantially non-compressible.

It will be evident from the foregoing that whether the pulley drives the belt, or is driven by it, any sudden starting or stopping movement of it will be cushioned by the resilient members i and 4, and that they will, consequently, materially reduce the strain that otherwise would be placed both on the belt and also on the machinery driven by the pulley, in the event that it operates as a driven pulley.

Under such conditions as those just described, it is important that the tractive effort transmitted through the cushioning material from the ribs of the rim sections to the walls of the recesses in the hub, or vice-versa, shall not produce any substantial camming action tending to force the rim sections outwardly. Any tendency of this nature is substantially eliminated in the construction shown by the fact that the ribs b and the sockets a, in which the ribs are located, are so shaped that ample portions of their surfaces through which the tractive effort is transmitted are positioned at approximately right angles to the line of traction, this line being the circumference passing substantially through the centers of the sockets and the ribs. While the complemental faces of these intermeshing parts do include inclined portions, some of which are located at the inner side of the line of traction, and others at the outer side of said line, the symmetrical nature of these ribs and grooves is such that any camming action created at the inner side of said line is substantially counter-balanced by the approximately equal and outer forces simultaneously created at the outer side of said line. In other words, any component so created in a direction tending to force the rim 3 outwardly is substantially balanced by an oppositely directed component of the same force so that no dominating component of any substantial value is created either inwardly or outwardly. If desired, also, each of the extensions g and the portions of the cushioning material 2' substantially surrounding them, may be shaped to form a suction cup 9' which, when covered by the belt, will have a tendency to increase the grip of the belt on the pulley.

While We have herein shown and described a typical embodiment of our invention, it will be evident that the invention may be embodied in other forms without departing from the spirit or scope thereof.

This application is a division of our copending application Serial No. 527,867, filed March 24, 1944.

Having thus described our invention, what we desire to claim as new is:

1. A pulley comprising a hub, a rim encircling said hub, one of said members being provided with ribs and the other with grooves in which said ribs are located, both the ribs and the grooves being in the line of the traction force transmitted from one of said members to the other, and cushioning means interposed between said rim and hub and substantially isolating them from each other, said cushioning means including parts located in said grooves and spacing said ribs from the walls of said grooves, the ribs being of greater width in a circumferential direction at intermediate points in their radial length than at other points in said length, and the grooves being of complemental form to receive said ribs, said points of maximum width of both the ribs and the grooves being positioned substantially in said line of traction as to avoid producing any dominant component of the traction force in a direction radially of the pulley, said cushioning means being free to expand and contract sumciently to cushion the transmission of shock from said hub to the rim, or vice-versa.

2. A pulley according to preceding claim 1, in which said rim is divided into circumferential sections, the ends of which are interlocked with each other through one or more cushioning elements.

3. A pulley according to preceding claim 1, in which said rim is divided into circumferential sections, and said cushioning means is divided into sections corresponding to said rim sections and associated, respectively, with the latter.

4. A pulley according to preceding claim 1, including retaining plates secured to the opposite sides of one of said pulley members and overlapping end portions of said cushioning member at the lateral surfaces of the pulley.

5. A pulley according to preceding claim 1, in which each of said ribs has opposite sides of approximately semi-cylindrical form.

SYDNEY T. FARRELL. FREDERICK L. FARRELL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,460,869 Thropp July 3, 1923 1,946,956 Waseige Feb. 13, 1934 

